The present invention relates to thermal decomposition using a fluidized bed for processing organic solid materials.
There have heretofore been proposed various types of thermal decomposition systems for thermally decomposing organic solid materials to obtain liquid or gaseous products. For example, methods of gasifying or liquifying coal include a method wherein the coal is thermally decomposed by externally supplied heat, and a further method in which part of the coal is directly burned for obtaining heat of combustion that is used as the heat source for the thermal decomposition of the remainder of the coal.
Also there are typical thermal decomposition furnaces of the fixed bed type, in which coal is thermally decomposed in stacked form within the thermal decomposition furnace, or of a fluidized bed type, wherein the coal is thermally decomposed while in a fluidized state above a grate within the furnace. As an example of the former type of furnace, a retort type continuous thermal decomposition furnace has been developed, and as an example of the latter type of furnace, there is a continuous or multi-stage fluidized bed type thermal decomposition furnace using at least two fluidized beds, one in a decomposition tower and one in a recovery tower.
While these thermal decomposition furnaces adopt the most suitable processing system and heat supplied system from various standpoints such as processed material, intended decomposition product to be recovered and economy, the heat supply system is particularly important and must be thoroughly investigated.
Assuming the case of thermally decomposing, for instance, urban rubbish as the organic solid material pertaining to the invention for the purpose of recovering useful oily (liquid) or gaseous substances by supplying the heat for the thermal decomposition from an external force, such thermal decomposition is not worthwhile at all in view of the conversion of the waste material into usable resources unless the recovered substance is more valuable in cost than the supplied energy.
Liquification or gasification of organic solid waste materials through dry distillation decomposition is now on the mid course of development, and various dry distillation decomposition methods have been proposed.